1999 NISSAN PRIMERA engine coolant

Component DescriptionNCEC0072The engine coolant temperature sensor is used to detect the
engine coolant temperature. The sensor modifies a voltage signal
from the ECM. The modified signal returns to the ECM as the
engine coolant temperature input. The sensor uses a thermistor
which is sensitive to the change in temperature. The electrical
resistance of the thermistor decreases as temperature increases.

Engine coolant temperature
ÉC (ÉF)Voltage*
VResistance
kW
þ10 (14)4.4 7.0 - 11.4
20 (68)3.5 2.1 - 2.9
50 (122)2.2 0.68 - 1.00
90 (194)0.9 0.236 - 0.260
*: These data are reference values and are measured between ECM terminal 70
(Engine coolant temperature sensor) and ECM terminal 48 (ECM ground).
CONSULT-II Reference Value in Data Monitor
Mode
NCEC0073
MONITOR ITEM CONDITION SPECIFICATION
COOLAN TEMP/SIEngine: After warming up More than 70ÉC (158ÉF)
On Board Diagnosis LogicNCEC0074
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0115
0115IAn excessively high or low voltage from the sensor is
sent to ECM.*IHarness or connectors
(The sensor circuit is open or shorted.)
IEngine coolant temperature sensor
*: When this malfunction is detected, the ECM enters fail-safe mode and the MI lights up.
Detected items Engine operating condition in fail-safe mode
Engine coolant tempera-
ture sensor circuitEngine coolant temperature will be determined by ECM based on the time after turning ignition switch
ªONº or ªSTARTº.
CONSULT-II displays the engine coolant temperature decided by ECM.
ConditionEngine coolant temperature decided (CONSULT-II
display)
Just as ignition switch is turned ON or Start 40ÉC (104ÉF)
More than approx. 4 minutes after ignition ON or
Start80ÉC (176ÉF)
Except as shown above40 - 80ÉC (104 - 176ÉF)
(Depends on the time)
When the fail-safe system for engine coolant temperature sensor is activated, the cooling fan operates
while the engine is running.
SEF594K
SEF012P
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR
(ECTS) (CIRCUIT)SR20DE
Component Description
EC-132

DTC Confirmation ProcedureNCEC0075NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
1) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Wait at least 5 seconds.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº, EC-
SR-135.
With GST
Follow the procedure ªWith CONSULT-IIº above.
PEF002P
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR
(ECTS) (CIRCUIT)SR20DE
DTC Confirmation Procedure
EC-133

Wiring DiagramNCEC0076
YEC082A
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR
(ECTS) (CIRCUIT)SR20DE
Wiring Diagram
EC-134

Diagnostic ProcedureNCEC0077
1 CHECK POWER SUPPLY
1. Turn ignition switch ªOFFº.
2. Disconnect engine coolant temperature sensor harness connector.
SEF205X3. Turn ignition switch ªONº.
4. Check voltage between terminal 2 and ground with CONSULT-II or tester.
SEF997WVoltage: Approximately 5V
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the harness for open or short between ECM and engine coolant temperature sensor.
©Repair harness or connectors.
3 CHECK GROUND CIRCUIT
1. Turn ignition switch ªOFFº.
2. Check harness continuity between engine coolant temperature sensor harness connector terminal 1 and engine ground.
Refer to wiring diagram.
Continuity should exist.
3. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 5.
NG©GO TO 4.
Front exhaust tube
FrontCoolant temperature
sensor harness
connector
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR
(ECTS) (CIRCUIT)SR20DE
Diagnostic Procedure
EC-135

Component InspectionNCEC0078ENGINE COOLANT TEMPERATURE SENSORNCEC0078S01Check resistance as shown in the figure.

Temperature ÉC (ÉF) Resistance kW
20 (68)2.1 - 2.9
50 (122)0.68 - 1.00
90 (194)0.236 - 0.260
If NG, replace engine coolant temperature sensor.
4 DETECT MALFUNCTIONING PART
Check the following.
IHarness for open or short between ECM and engine coolant temperature sensor
IHarness for open or short between engine coolant temperature sensor and TCM (Transmission control module)
©Repair open circuit or short to ground or short to power in harness or connectors.
5 CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to ªComponent Inspectionº, EC-SR-136.
OK or NG
OK©GO TO 6.
NG©Replace engine coolant temperature sensor.
6 CHECK INTERMITTENT INCIDENT
Perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-SR-114.
©INSPECTION END
SEF152P
SEF012P
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR
(ECTS) (CIRCUIT)SR20DE
Component Inspection
EC-136

DescriptionNCEC0248SYSTEM DESCRIPTIONNCEC0248S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS) Engine speed
EVAP can-
ister purge
controlEVAP canister purge volume
control solenoid valve Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Battery Battery voltage
Ignition switch Start signal
Closed throttle position switch Closed throttle position
Throttle position sensor Throttle position
Heated oxygen sensor 1 (front)Density of oxygen in exhaust gas
(Mixture ratio feedback signal)
Vehicle speed sensor or ABS actuator and
electric unit (control unit)Vehicle speed
This system controls flow rate of fuel vapor from the EVAP canis-
ter. The opening of the vapor by-pass passage in the EVAP canis-
ter purge volume control solenoid valve changes to control the flow
rate. The EVAP canister purge volume control solenoid valve
repeats ON/OFF operation according to the signal sent from the
ECM. The opening of the valve varies for optimum engine control.
The optimum value stored in the ECM is determined by consider-
ing various engine conditions. When the engine is operating, the
flow rate of fuel vapor from the EVAP canister is regulated as the
air flow changes.
COMPONENT DESCRIPTIONNCEC0248S02The EVAP canister purge volume control solenoid valve uses a
ON/OFF duty to control the flow rate of fuel vapor from the EVAP
canister. The EVAP canister purge volume control solenoid valve
is moved by ON/OFF pulses from the ECM. The longer the ON
pulse, the greater the amount of fuel vapor that will flow through the
valve.
CONSULT-II Reference Value in Data Monitor
Mode
NCEC0249
MONITOR ITEM CONDITION SPECIFICATION
PURG VOL C/VIEngine: RunningVehicle stopped 0%
Vehicle running Ð
SEF337U
DTC P0443 EVAP CANISTER PURGE VOLUME CONTROL
SOLENOID VALVE (CIRCUIT)SR20DE
Description
EC-250

DescriptionNCEC0279SYSTEM DESCRIPTIONNCEC0279S01
Sensor Input Signal to ECMECM func-
tionActuator
Camshaft position sensor Engine speed
ECM IACV-AAC valve Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Throttle position sensor Throttle position
PNP switch Park/Neutral position
Air conditioner switch Air conditioner operation
Power steering oil pressure switch Power steering load signal
Battery Battery voltage
Vehicle speed sensor or ABS actuator and
electric unit (control unit)Vehicle speed
Cooling fan Cooling fan operation
Electrical load Electrical load signal
This system automatically controls engine idle speed to a specified
level. Idle speed is controlled through fine adjustment of the
amount of air which by-passes the throttle valve via IACV-AAC
valve. The IACV-AAC valve changes the opening of the air by-pass
passage to control the amount of auxiliary air. This valve is actu-
ated by a step motor built into the valve, which moves the valve in
the axial direction in steps corresponding to the ECM output sig-
nals. One step of IACV-AAC valve movement causes the respec-
tive opening of the air by-pass passage. (i.e. when the step
advances, the opening is enlarged.) The opening of the valve is
varied to allow for optimum control of the engine idling speed. The
crankshaft position sensor (POS) detects the actual engine speed
and sends a signal to the ECM. The ECM then controls the step
position of the IACV-AAC valve so that engine speed coincides with
the target value memorized in ECM. The target engine speed is the
lowest speed at which the engine can operate steadily. The opti-
mum value stored in the ECM is determined by taking into consid-
eration various engine conditions, such as during warm up,
deceleration, and engine load (air conditioner, power steering, cool-
ing fan operation and electrical load).
COMPONENT DESCRIPTIONNCEC0279S02The IACV-AAC valve is operated by a step motor for centralized
control of auxiliary air supply. This motor has four winding phases
and is actuated by the output signals of ECM which turns ON and
OFF two windings each in sequence. Each time the IACV-AAC
valve opens or closes to change the auxiliary air quantity, the ECM
sends a pulse signal to the step motor. When no change in the
auxiliary air quantity is needed, the ECM does not issue the pulse
signal. A certain voltage signal is issued so that the valve remains
at that particular opening.
SEF937W
DTC P0505 IDLE AIR CONTROL VALVE (IACV) Ð
AUXILIARY AIR CONTROL (AAC) VALVESR20DE
Description
EC-263

System DescriptionNCEC0433COOLING FAN CONTROLNCEC0433S01
Sensor Input Signal to ECMECM func-
tionActuator
Vehicle speed sensor or ABS actuator and
electric unit (control unit)Vehicle speed
ECM Cooling fan relay(s) Engine coolant temperature sensor Engine coolant temperature
Air conditioner switch Air conditioner ªONº signal
Ignition switch Start signal
Refrigerant pressure sensor Refrigerant pressure
The ECM controls the cooling fan corresponding to the vehicle speed, engine coolant temperature, refriger-
ant pressure, and air conditioner ON signal. The control system has ON-OFF control.
The refrigerant pressure sensor uses an electrostatic volume pressure transducer to convert refrigerant pres-
sure to voltage. The transducer is installed in the liquid tank of the air conditioner system.
OPERATIONNCEC0433S02
SEF099X
SEF198X Refrigerant pressure is less than 1.76 Mpa.
Refrigerant pressure is between 1.76 Mpa and 2.06 Mpa.Refrigerant pressure is above 2.06 Mpa. 20 (12) 80 (50)
Vehicle speed km/h (MPH)
20 (12) 80 (50)
Vehicle speed km/h (MPH)20 (12) 80 (50)
Vehicle speed km/h (MPH)Cooling fans operate
at ªHighº speed.
Cooling fans operate
at ªLowº speed.
Cooling fans
do no operate 105 (221)
100 (212)
95 (203) 105 (221)
100 (212)
95 (203)105 (221)
100 (212)
95 (203)
Engine coolant temperature
ÉC (ÉF)
Engine coolant temperature
ÉC (ÉF)
Engine coolant temperature
ÉC (ÉF)
DTC P1217 OVERHEAT (COOLING SYSTEM)SR20DE
System Description
EC-279